ON KINETICS OF MICROEMULSION COPOLYMERIZATION OF BUTYL ACRYLATE AND ACRYLONITRILE

The oil-in-water microemulsion copolymerizations of butyl acrylate and acrylonitrile initiated by water (ammonium peroxodisulfate, AP)-and o il (dibenzoyl peroxide, DBP)-soluble radical initiators were investiga ted. Copolymerizations show two distinct nonstationary rate regions. T he maximum rate of polymerization is found to be proportional to the 0 .48th and 0.65th power of the AP and DBP concentration, respectively. The rate per particle is found to be proportional to the 0.05th and 0. 2nd power of the AP and DBP concentration, respectively. The rate of p olymerization decreases with increasing the acrylonitrile concentratio n. The number of particle increases with increasing conversion up to 5 0-70%. The number-average molecular weight increases with conversion u p to ca. 20% and then decreases. The number-average molecular weights were found to decrease with increasing the concentration of both initi ator and acrylonitrile. The experimental results were discussed in ter ms of the water-phase polymerization, the chain-transfer and radical d esorption events, the particle nucleation during the whole polymerizat ion, and recruiting monomer and emulsifier from the free monomer-swoll en emulsifier micelles. (C) 1996 John Wiley & Sons, Inc.